OCR MEI FP1 2010 June — Question 2 6 marks

Exam BoardOCR MEI
ModuleFP1 (Further Pure Mathematics 1)
Year2010
SessionJune
Marks6
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicMatrices
TypeSolving linear systems using matrices
DifficultyModerate -0.3 This is a straightforward Further Maths question testing basic matrix operations: extracting equations from matrix form, finding a 2×2 inverse using the standard formula, and multiplying to solve. While it's Further Maths content, the mechanical nature and standard textbook format make it slightly easier than average overall, though harder than typical Core questions on the same techniques.
Spec4.03a Matrix language: terminology and notation4.03n Inverse 2x2 matrix4.03r Solve simultaneous equations: using inverse matrix

2 You are given that \(\mathbf { M } = \left( \begin{array} { r r } 2 & - 5 \\ 3 & 7 \end{array} \right)\). \(\mathbf { M } \binom { x } { y } = \binom { 9 } { - 1 }\) represents two simultaneous equations.
  1. Write down these two equations.
  2. Find \(\mathbf { M } ^ { - 1 }\) and use it to solve the equations.

Question 2(i):
AnswerMarks Guidance
AnswerMark Guidance
\(2x - 5y = 9\)B1
\(3x + 7y = -1\)B1 [2]
Question 2(ii):
AnswerMarks Guidance
AnswerMark Guidance
\(M^{-1} = \frac{1}{29}\begin{pmatrix} 7 & 5 \\ -3 & 2 \end{pmatrix}\)M1, A1 [2] Divide by determinant; c.a.o.
\(\frac{1}{29}\begin{pmatrix} 7 & 5 \\ -3 & 2 \end{pmatrix}\begin{pmatrix} 9 \\ -1 \end{pmatrix} = \frac{1}{29}\begin{pmatrix} 58 \\ -29 \end{pmatrix}\)M1, A1(ft) [2] Pre-multiply by their inverse; for both
\(\Rightarrow x = 2, y = -1\)
# Question 2(i):

| Answer | Mark | Guidance |
|--------|------|----------|
| $2x - 5y = 9$ | B1 | |
| $3x + 7y = -1$ | B1 **[2]** | |

---

# Question 2(ii):

| Answer | Mark | Guidance |
|--------|------|----------|
| $M^{-1} = \frac{1}{29}\begin{pmatrix} 7 & 5 \\ -3 & 2 \end{pmatrix}$ | M1, A1 **[2]** | Divide by determinant; c.a.o. |
| $\frac{1}{29}\begin{pmatrix} 7 & 5 \\ -3 & 2 \end{pmatrix}\begin{pmatrix} 9 \\ -1 \end{pmatrix} = \frac{1}{29}\begin{pmatrix} 58 \\ -29 \end{pmatrix}$ | M1, A1(ft) **[2]** | Pre-multiply by their inverse; for both |
| $\Rightarrow x = 2, y = -1$ | | |

---
2 You are given that $\mathbf { M } = \left( \begin{array} { r r } 2 & - 5 \\ 3 & 7 \end{array} \right)$.\\
$\mathbf { M } \binom { x } { y } = \binom { 9 } { - 1 }$ represents two simultaneous equations.\\
(i) Write down these two equations.\\
(ii) Find $\mathbf { M } ^ { - 1 }$ and use it to solve the equations.

\hfill \mbox{\textit{OCR MEI FP1 2010 Q2 [6]}}